In the packaging industry, over the last few years, there has been an important evolution of the types of materials (such as polyethylene, polypropylene, biodegradable plastic, recycled plastic, paper, etc. . . . ) and types of construction (such as inner liner, woven, special printing, coating, etc. . . . ) to name a few, used to make bags. This has led to a wide range of bags that are more or less flexible and more or less porous, which must be declined in an extensive variation of bag sizes to fit the different industries and ever-growing market requirements. Furthermore, over the last decade, globalization of bag suppliers into the packaging market, introduced bags of a great variability of quality. This gave rise to high quality bags, but also low quality bags (such as bags stuck together, damaged, poorly stacked and varying in dimensions for a given size). Overall, the evolution of the context resulted in considerable variability of bags.
Paradoxically, in conjunction with the arrival on the market of this wide variety of empty bags, expectations in terms of finished filled bags quality (namely in terms of appearance) are constantly increasing along with the desire to have single automatic equipment to process most types of bags as possible, ideally all types.
Of course, automated packaging equipment is constructed to be as efficient as possible in a given application. For the sake of cost optimization, it is common for producers to try to stretch the scope of their equipment, leading often to bags with defaults or rejected bags (during the packaging or later in the process), mostly coming from bags that have not been well prepared before the filling step. Such a miss preparation may result in improperly filled bags as well as improperly sealed (non-hermetic) bags which can cause quality problems in terms of hygiene, preservation and contamination, as well as in terms of appearance of the filled finished bags, ultimately resulting in producers' or customers' dissatisfaction.
It is important to remember that there are four major steps involved in packaging equipment used to bag bulk products: 1) preparing, 2) filling, 3) sealing and 4) evacuating the bag. The present invention mainly relates to the preparing step, which is responsible for executing the following basic actions:                Grabbing,        Conditioning,        Unstacking,        Opening,        Transporting, and        Installing the bag on the filling point.Some of these actions can be switchable or combined from one equipment to another, along with an optional action, forming the bag, which is only necessary in some applications (for example with equipment using film rolls).        
Initially, packaging of products intended for the food, pet food, feed, seed and chemical industries, to name a few, was done manually. Later, the automation of packaging equipment began in order to reduce health and safety issues as well as costs related to labor, while accelerating the packaging process and making it more consistent, providing a better quality as much as possible.
Progressively, the automation of packaging equipment was applied to all four steps of packaging. Initially, it has been done through systems with limited degrees of freedom implying displacement of a bag from an initial point to a final point, including the accomplishment of different actions, according to pre-defined, invariable and back and forth movements usually realized by dedicated devices. As used herein, the term “degrees of freedom” is related to the robot (or displacement device) movements associated to its rotation axes which result in flexibility. Refer to FIG. 1A showing a prior art system for a better understanding of the different principles involved.
Later, in order to gain flexibility of movements, the automation of packaging equipment has gone to systems with more degrees of freedom. These systems started to automate different packaging steps, as seen in patent application PCT/CA2010/001940 which describes a system automating the closing step, or U.S. Ser. No. 61/382,279 which describes a system automating the filling step.
Considering the complexity of preparing bags which can vary in type of material, type of construction, size and quality, the automation of the preparing step has become a challenge. In fact, the use of 3 to 4 degrees of freedom systems (in the preparing step) operate in limited applications since they can hardly efficiently handle porous, flexible, poorly stacked and/or bag of varying dimensions (for a given size).
Later, in order to handle a greater range of bags, the automation of the preparing step started to be done using systems with 5 to 6 degrees of freedom. In existing baggers, mostly open-mouth baggers, the preparing step including the accomplishment of specific required actions, usually implies the displacement of an empty bag from an initial point to a final point (filling point), integrating one (or many) location evaluation of the bag allowing a correction of the bag location or location of the gripping device taking the bag which are equivalent since both types of correction result in a correction preceding a defined movement. In fact, the goal is to correct the location of the bag in order to move it in a known (and defined) location and displace it according to pre-defined, invariable and back and forth movements realized most of the time by various dedicated devices. These dedicated devices grab the bag in a defined location and transfer it to another dedicated device (in a defined location). Since location evaluation is very complex to achieve on a stack of bags, there is a need to combine it with an upstream dedicated unstacker to bring only one bag in a known (and defined) location. Despite the fact that such system is more tolerant to variations in dimensions (for a given size), these 5 to 6 degrees of freedom systems do not provide improvements concerning efficient handling of porous and flexible bags. To achieve an efficient handling, such equipment would require the addition of new devices in terms of unstacking and location evaluation. This would prevent, for example, softer bags from deforming and make the system more effective with a large variety of stacked bags. Consequently, it would make this machine much too expensive and complex.
By analysing the prior art, one can notice that in the field of automation of packaging equipment, it has been difficult to find an effective way to automate the preparing step in order to deal with large variety of bags including more porous, flexible, poorly stacked and/or bags varying in dimensions (for a given size); while being able to provide a finished filled bag fulfilling an expected quality at high speed.
Therefore, there are presently needs for a simple, fully automated and rapid automated system (with 5 to 6 degrees of freedom) for better preparing bags by exploiting deeper all the existing degrees of freedom in order to process different types of bags and providing finished filled bags of expected quality and less rejected bags.